An accumulator type fuel injection device, used for diesel engines, is disclosed in Japanese Patent Application Laid Open No. 165858-1984. In this fuel injection device, fuel high pressure sent from a high pressure fuel pump is stored in a surge tank referred to as a common rail, and the stored fuel is injected into an engine when an injection valve is opened. An appropriate fuel injection device is disclosed in Japanese Patent Application Laid Open No. 159366-1985 in which a safety device is provided in the fuel passage to an injection valve, and when at least a predetermined amount of fuel is supplied to the injection valve, the fuel supply passage is closed.
However, very high pressure (for example, 150 Mpa) is stored in the common rail, so that a portion of the ultra-high pressure fuel passage provided from the high pressure fuel pump to the injection valve, through the common rail, may become damaged and high pressure fuel may leak out. Also reflection pressure waves, generated by an injection valve of one cylinder, may be transmitted to other cylinders through the common rail, so that the opening and closing timing of the cylinder is affected changing the injection amount and timing.
It is a primary object of the present invention to improve the reliability of a fuel injection system by providing a mechanism which maintains high pressure fuel in a common rail even when a high pressure fuel passage connected to the common rail, for example, an injection pipe between the common rail and the injection valve, or a supply pipe between the high pressure supply pump and the common rail, is damaged, or by providing a mechanism which prevents the occurrence of pulsations of high pressure fuel.